Adjustment of ecosystem root respiration to warmer climatic conditions can alter the autotrophic
portion of soil respiration and influence the amount of carbon available for biomass production.
We examined 44 published values of annual forest root respiration and found an increase in
ecosystem root respiration with increasing mean annual temperature (MAT), but the rate of this
cross-ecosystem increase (Q10 = 1.6) is less than published values for short-term responses of
root respiration to temperature within ecosystems (Q10 = 2 to 3). When specific root respiration
rates and root biomass values were examined, there was a clear trend for decreasing root
metabolic capacity (respiration rate at a standard temperature) with increasing MAT. There also
were tradeoffs between root metabolic capacity and root system biomass, such that there were no
instances of high growing season respiration rates and high root biomass occurring together. We
also examined specific root respiration rates at three soil warming experiments at Harvard Forest,
USA, and found decreases in metabolic capacity for roots from the heated plots. This decline
could be due to either physiological acclimation or to the effects of co-occurring drier soils on
the measurement date. Regardless of the cause, these findings clearly suggest that modeling
efforts that allow root respiration to increase exponentially with temperature, with Q10 values of
2 or more, may over-predict root contributions to ecosystem CO2 efflux for future climates and
underestimate the amount of C available for other uses, including NPP.

Recent patterns and projections of climatic change have focused increased scientific and public attention on patterns of carbon (C) cycling and its controls, particularly the factors that determine whether an ecosystem is ...

Extreme precipitation is predicted to be more frequent and intense accompanying global
warming, and may have profound impacts on soil respiration (Rs) and its components, i.e.,
autotrophic (Ra) and heterotrophic (Rh) ...

The direct respiration of sinking organic matter by attached bacteria is often invoked as the dominant sink for settling particles in the mesopelagic ocean. However, other processes, such as enzymatic solubilization and ...

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